[R] ggplot2 problem

[steve]

I'm using ggplot2 2.0.8 and R 2.8.0

df = data.frame(Year = rep(1:5,2))
m = ggplot(df, aes(Year=Year))
m + geom_bar()

Error in get("calculate", env = ., inherits = TRUE)(., ...) :
   attempt to apply non-function